Windows implements SNTP. The goal is to keep the clock within tolerance for Kerberos (5 minutes). It's embarrassingly bad but they don't seem to have any real reason to fix it. Also the w32tm code is ... bad.
At least NTP works on windows I have been trying to migrate a small 15 mac office to use networked users - because of the changes apple made to NTP all the networked macs lose sync after a couple of hours and crash quite often screwing up the outlook database.
It's certainly soured me on apple period I am recommending getting some nice dell i7 hexcore work stations.
